Amid a surge in COVID-19 cases fueled by the highly-contagious Delta variant comes a dose of good news: Moderna’s vaccine is holding up. The drug maker said Thursday its COVID-19 shot was still 93% effective six months after a second dose. That nearly matches its 94% efficacy rate shown in the original clinical trial. And Moderna’s shots are holding up better than the one by Pfizer and BioNTech, whose efficacy, the two companies said, declined to around 84% six months after the second shot. Both Pfizer-BioNTech’s and Moderna’s vaccines are two-shot regimens based on the novel messenger RNA technology. Despite that efficacy rate, Moderna said a booster shot will be needed before the winter season. It said its studies of booster candidates triggered robust antibody responses against viral variants such as Delta and others. Health officials worldwide are currently debating whether more doses are safe, effective and necessary. Pfizer, a vocal proponent of booster shots, plans to seek U.S. and European approval for a third shot later this month. It’s ahead of Moderna in the production race. Pfizer plans to make as many as 3 billion COVID-19 vaccine doses this year. Moderna aims to produce up to 1 billion.